D&D uses a standard “hexagonal” mapping system that dates back to the very origins of the game. The first map for the wilderness was the map from another game entirely: Avalon Hill’s Outdoor Survival game. Both Avalon Hill and SPI used hex maps in their games and it was natural that D&D followed suit. Hex maps have many great advantages. You can use a D6 to determine random directions and movement is easier to calculate than it would be with other models. Traveller also adopted hexagon mapping, perhaps with even greater attention to standardization and detail. The Judges Guild added numbers to each hex so that the DM could refer back to their notes to see what that particular hex contained. That company also developed more elaborate sub-mapping systems, so that greater detail could be shown on hex maps within the standard hex.